Data visualisation — introduction
2024-09-07
At the end of this topic you should be able to
Understand the basic principles of data visualization
Understand how human brains perceive colour
Know which visual attributes or channels are most effective
Know how to represent different kinds of data visually
Basic understanding of how to produce visualizations using the ggplot2 package
Chapter 1, Data visualization, in r4ds
For Friday if you can
Some data visualizations are better than others
Some data visualizations are better than others
Aesthetic
Tacky, tasteless, ugly, hodgepodge, inconsistent design
Substantive
Graph has problems because of the data being presented
Perceptual
Inspite of good taste and good data, a graph may be confusing or misleading because of how people perceive and process what they are looking at
Drawing a graph involves mapping data to visual attributes — some more effective than others
"#AA6633"A colour palette is a the colour scheme or selection used to represent data or design on a graph
Want more than a numerical mapping — want perceptually uniform mappings
discrete
sequential
diverging
Categorical data
Easily distinguishable
Favour no one colour
Vary H, constant C & L
Continuous data
Brightness & intensity of colour vary
Vary C & L, constant H
Continuous data
Can vary everything if careful
Vary H, C & L
Continuous data where mid-point means something (0)
Single hue in each arm
C & L are balanced in each arm
C goes to 0 at mid-point
Luminance is not linear or even monotonic
Colour vision deficiency
Decreased ability to see colour or differences in colour
Can you see the green squares?
Some shapes, colours, angles more easy to spot
Can happen before (or almost before) before consciously looking at something
several stand-your-ground obama-graduates https://x.com/MathCurmudgeon/status/1828175452080320967
happiest countries https://x.com/TheEditorDiary/status/1742939764003893567
man vs animal https://x.com/geospacedman/status/1828708146786816476
renzo pie chart https://x.com/witconomist/status/1828570268635451491